Magnetic resonance imaging · 2026
Efficient B1+ modeling for fast quantification of PDFF and two-compartment T1, T2* relaxation times in abdominal MRI of steatotic patients at 1.5 T.
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Kouakou Kouame Ferdinand, Paisant Anita, Arnould Laurent, Aube Christophe, Saint-Jalmes Hervé
Аннотация
PURPOSE: To propose and preliminarily evaluate a rapid method with potential clinical applicability for correcting the B1+ spatial variation in quantitative abdominal MRI.
MATERIALS AND METHODS: The 3D VFA method allows rapid quantification of the T1 relaxation time and is particularly suitable for abdominal imaging, but requires mapping of the B1+ field throughout the 3D volume, which is often not available on clinical MRI scanners. The proposed method, called B1MM, combines a rapid 2D mapping of the B1+ field with modelling of the excitation coil properties to generate a B1+ mapping over a large 3D volume. The method was first validated on phantoms and a healthy volunteer against reference T1-mapping techniques. The method was then applied to simultaneously estimate PDFF, T1, and T2* in the liver, abdominal muscles, and fat of six patients with steatosis using a VFA-based two-compartment model. The six patients were scanned on a 1.5 T clinical MRI (Magnetom Sola, Siemens Healthineers, Erlangen) with a total protocol duration of 25 s. A comparison of the results with and without angle correction and with the literature was performed.
RESULTS: In both phantoms and the volunteer, angle correction brought T1 values close to the reference. In the six patients, as expected, angle correction had no effect on PDFF or T2*, but it markedly reduced T1 variability and improved T1 measurement accuracy. In addition, the total acquisition time is considerably reduced, which improves patient comfort.
MATERIALS AND METHODS: The 3D VFA method allows rapid quantification of the T1 relaxation time and is particularly suitable for abdominal imaging, but requires mapping of the B1+ field throughout the 3D volume, which is often not available on clinical MRI scanners. The proposed method, called B1MM, combines a rapid 2D mapping of the B1+ field with modelling of the excitation coil properties to generate a B1+ mapping over a large 3D volume. The method was first validated on phantoms and a healthy volunteer against reference T1-mapping techniques. The method was then applied to simultaneously estimate PDFF, T1, and T2* in the liver, abdominal muscles, and fat of six patients with steatosis using a VFA-based two-compartment model. The six patients were scanned on a 1.5 T clinical MRI (Magnetom Sola, Siemens Healthineers, Erlangen) with a total protocol duration of 25 s. A comparison of the results with and without angle correction and with the literature was performed.
RESULTS: In both phantoms and the volunteer, angle correction brought T1 values close to the reference. In the six patients, as expected, angle correction had no effect on PDFF or T2*, but it markedly reduced T1 variability and improved T1 measurement accuracy. In addition, the total acquisition time is considerably reduced, which improves patient comfort.